linux-kernel - [PATCH v2 3/6] KVM: arm64: Allow userspace to inject external instruction aborts

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Message-ID: <20250604050902.3944054-4-jiaqiyan@google.com>
Date: Wed,  4 Jun 2025 05:08:58 +0000
From: Jiaqi Yan <jiaqiyan@...gle.com>
To: maz@...nel.org, oliver.upton@...ux.dev
Cc: joey.gouly@....com, suzuki.poulose@....com, yuzenghui@...wei.com, 
	catalin.marinas@....com, will@...nel.org, pbonzini@...hat.com, corbet@....net, 
	shuah@...nel.org, kvm@...r.kernel.org, kvmarm@...ts.linux.dev, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	linux-doc@...r.kernel.org, linux-kselftest@...r.kernel.org, 
	duenwen@...gle.com, rananta@...gle.com, jthoughton@...gle.com, 
	Jiaqi Yan <jiaqiyan@...gle.com>
Subject: [PATCH v2 3/6] KVM: arm64: Allow userspace to inject external
 instruction aborts

From: Raghavendra Rao Ananta <rananta@...gle.com>

When KVM returns to userspace for KVM_EXIT_ARM_SEA, the userspace is
encouraged to inject the abort into the guest via KVM_SET_VCPU_EVENTS.

KVM_SET_VCPU_EVENTS currently only allows injecting external data aborts.
However, the synchronous external abort that caused KVM_EXIT_ARM_SEA
is possible to be an instruction abort. Userspace is already able to
tell if an abort is due to data or instruction via kvm_run.arm_sea.esr,
by checking its Exception Class value.

Extend the KVM_SET_VCPU_EVENTS ioctl to allow injecting instruction
abort into the guest.

Signed-off-by: Raghavendra Rao Ananta <rananta@...gle.com>
Signed-off-by: Jiaqi Yan <jiaqiyan@...gle.com>
---
 arch/arm64/include/uapi/asm/kvm.h |  3 ++-
 arch/arm64/kvm/arm.c              |  1 +
 arch/arm64/kvm/guest.c            | 13 ++++++++++---
 include/uapi/linux/kvm.h          |  1 +
 4 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index ed5f3892674c7..643e8c4825451 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -184,8 +184,9 @@ struct kvm_vcpu_events {
 		__u8 serror_pending;
 		__u8 serror_has_esr;
 		__u8 ext_dabt_pending;
+		__u8 ext_iabt_pending;
 		/* Align it to 8 bytes */
-		__u8 pad[5];
+		__u8 pad[4];
 		__u64 serror_esr;
 	} exception;
 	__u32 reserved[12];
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 99e0c6c16e437..78e8a82c38cfc 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -319,6 +319,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_ARM_IRQ_LINE_LAYOUT_2:
 	case KVM_CAP_ARM_NISV_TO_USER:
 	case KVM_CAP_ARM_INJECT_EXT_DABT:
+	case KVM_CAP_ARM_INJECT_EXT_IABT:
 	case KVM_CAP_SET_GUEST_DEBUG:
 	case KVM_CAP_VCPU_ATTRIBUTES:
 	case KVM_CAP_PTP_KVM:
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 2196979a24a32..4917361ecf5cb 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -825,9 +825,9 @@ int __kvm_arm_vcpu_get_events(struct kvm_vcpu *vcpu,
 		events->exception.serror_esr = vcpu_get_vsesr(vcpu);
 
 	/*
-	 * We never return a pending ext_dabt here because we deliver it to
-	 * the virtual CPU directly when setting the event and it's no longer
-	 * 'pending' at this point.
+	 * We never return a pending ext_dabt or ext_iabt here because we
+	 * deliver it to the virtual CPU directly when setting the event
+	 * and it's no longer 'pending' at this point.
 	 */
 
 	return 0;
@@ -839,6 +839,7 @@ int __kvm_arm_vcpu_set_events(struct kvm_vcpu *vcpu,
 	bool serror_pending = events->exception.serror_pending;
 	bool has_esr = events->exception.serror_has_esr;
 	bool ext_dabt_pending = events->exception.ext_dabt_pending;
+	bool ext_iabt_pending = events->exception.ext_iabt_pending;
 
 	if (serror_pending && has_esr) {
 		if (!cpus_have_final_cap(ARM64_HAS_RAS_EXTN))
@@ -852,8 +853,14 @@ int __kvm_arm_vcpu_set_events(struct kvm_vcpu *vcpu,
 		kvm_inject_vabt(vcpu);
 	}
 
+	/* DABT and IABT cannot happen at the same time. */
+	if (ext_dabt_pending && ext_iabt_pending)
+		return -EINVAL;
+
 	if (ext_dabt_pending)
 		kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
+	else if (ext_iabt_pending)
+		kvm_inject_pabt(vcpu, kvm_vcpu_get_hfar(vcpu));
 
 	return 0;
 }
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 4fed3fdfb13d6..2fc3775ac1183 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -943,6 +943,7 @@ struct kvm_enable_cap {
 #define KVM_CAP_ARM_EL2 240
 #define KVM_CAP_ARM_EL2_E2H0 241
 #define KVM_CAP_ARM_SEA_TO_USER 242
+#define KVM_CAP_ARM_INJECT_EXT_IABT 243
 
 struct kvm_irq_routing_irqchip {
 	__u32 irqchip;
-- 
2.49.0.1266.g31b7d2e469-goog